/cc @bcmills

Why is it important that the cache location to be independent of GOPATH? (That is, why can't your CI system save $GOPATH/pkg/mod where it is?)

You could also change GOPATH itself, and set GO111MODULE=on if needed - that's what I did when I needed to change the module cache location for GitLab CI to be able to store it. I don't remember the exact issue I had but I think it was similar to yours.

@bcmills: Why is it important that the cache location to be independent of GOPATH? (That is, why can't your CI system save $GOPATH/pkg/mod where it is?)

It was basically more like a question. I am coming from the old godep since a while, where there was a GODEPCACHE env, but there is honestly no technical limitation for this as of now, as lined out by @dpinela . I could just put the whole GOPATH into that cache folder. And because of the flexibility I have in gitlab-ci, I can also decide myself if I want specific GOPATH/* folders to be included in the cache or not.

I'm currently overthinking my whole suggestion and writing down my thoughts:

• Thanks to go modules, the GOPATH itself as a whole is kind of a cache for different things now (Not exactly, but you probably can see what I mean) and lost a bit of "importance" for projects.
• Depending on the use-case, we could possibly see GOBIN as deprecated, but I can definitely see some cases where you want GOBIN somewhere else than GOPATH/bin (and also for compatibility for sure)
• If, in the future, there's a new feature requiring a new folder within GOPATH, you'd have to think again about introducing a new env variable for that. If we/you just don't add them, it will be the same idiomatic way golang approaches, keeping it simple and clear (where GOPATH is the entrypoint for everything). And once there is a real requirement for it, we can have a look into that specificly

I could see this closed, I was thinking too much "the old way" and there's no technical requirement as of now

Here's a reason I think this could be helpful.

With go env -w, I can globally set env variables on CI, such as GOCACHE, CGO_ENABLED, or GOBIN.

Unfortunately, many environments explicitly set GOPATH - including the official Docker images, for example. So I can't just do something like go env -w GOPATH=/cache/gopath.

The answer here could be "simply override the GOPATH env var", but that's difficult to do in some environments. For example, Drone CI has no way to set global environment variables, so I have to repeat it at every build step. This is the kind of thing that I hoped go env -w would simplify.

This would indeed be fixed by a GOMODCACHE, since then I'd do something like go env -w GOMODCACHE=/cache/modcache GOCACHE=/cache/buildcache.

@dionysius you can copy the cache inside the project folder and then cache it with gilabci -- before building you move the cache back in $GOPATH/pkg/mod

e.g.
cp -r $GOPATH/pkg/mod ./modcache
ci yaml: cache: paths: - modcache/
before go build:
ci yaml: before_script:
cp -r ./modcache $GOPATH/pkg/mod

or use vendor and set in ci:

variables:
 GOFLAGS: -mod=vendor

What if I would like to set the cache on a RAMDISK (and not wear the SSD)?

@TudorHulban GOMODCACHE was implemented in #34527, and it will ship with Go 1.15.

Wooooow! Good to hear!